Mobile number numerology

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Description adds value beyond annotations: 'read-only deterministic arithmetic over a fixed number table -- no ephemeris, no network lookup, no writes, no auth, at least 30 requests/min/IP per server instance.' Annotations already declare readOnlyHint, idempotentHint, destructiveHint; description provides concrete details.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, no waste. First sentence lists outputs, second gives usage guidance and behavioral details. Front-loaded with key purpose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Even without output schema, description lists all return values (digit string, total, etc.). Also covers rate limit, authentication, and distinguishes from sibling. Complete for a deterministic read-only tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has one parameter with 100% description coverage. Description adds context: accepts various formats like +91 98765-43210, strips non-digits, must contain at least one non-zero digit. This exceeds schema description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states it returns numerological reading of a phone number, listing specific outputs (digit string, total, reduced number, vibe, meaning). Distinct from sibling get_numerology by specifying it's for phone numbers only, not birth dates.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly says to use for 'is my phone number lucky' style questions or when choosing candidate numbers. Also states when not to use: for birth date queries, use get_numerology.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.